The present invention relates to improvements in waste processing, in particular the invention relates to the processing of waste material containing a polymer metal mix, for example waste insulated electrical cable.
With diminishing resources and an increasing cost of oil it is becoming increasingly important that materials are recycled and not put into landfill. Furthermore it is increasingly important that waste materials are processed locally and are not, for example, shipped overseas where they can be disposed of in regimes having less harsh statutory requirements relating to pollution and the processing of waste.
When materials containing substantial quantities of metal are to be processed it is usual to separate the metal from the remainder of the waste and to clean it for re-use. However, when the metals are coated in other substances this can prove to be difficult and specialized processes are used for removing the coatings. One such process is described in WO/2004 059229 and WO/2006 100512 in the name of Al Chalabi et al, in which a de-coating method is described. While this method is effective for recovering the metal and energy is recovered from the non metal components there are several problems associated with this technology when trying to recycle material substantially comprising a low melting point plastic and metal. Firstly, as the plastic melts the waste will stick together and stick to the sides of the oven and accordingly will not tumble through the oven as is intended to happen. Secondly the plastic is pyrolysed and is not recovered from the process. Accordingly, although energy is recovered from the plastic component of the waste it cannot be reused.
Currently, where it is desirable for the plastic to be recycled from the waste the waste is shipped to countries having a low labor cost and the plastic is manually separated from the metal, for example the insulation is manually stripped from copper wire. In this manner both the plastic and the metal can be sold on to be recycled into new products. While this method is effective it is not financially viable for manual separation in many countries as the cost of labor is too high in comparison to the value of the plastics recovered.
It is the purpose of the present invention to provide an improved waste processing system that at least in part mitigates the above mentioned problems.